The primary objective of our current research is to identify differences between normal and malignant cells in their basic growth requirements and/or in their responses to normal growth regulatory signals that might be useful in the design of innovative approaches to cancer therapy. Direct comparisons are being made of normal and malignantly transformed cells that share a common species and cell type of origin. We can grow normal human keratinocytes and comparable squamous cell carcinoma lines in defined media and are in the process of making detailed comparisons of their quantitative growth requirements. We can grow normal human mammary epithelial cells in a defined medium and expect to begin comparisons with breast cancer lines in the near future. Studies of the growth requirements of normal human melanocytes and human melanomas have been initiated. We have developed defined media for rat mammary carcinoma line 64-24 and rat mammary stromal cells and are studying the growth requirements of rat mammary epithelial cells. We have also extended the goals of this project temporarily to include a study of the growth requirements of human microvascular endothelial cells until alternative support can be found for that project. We have optimized a basal nutrient medium that supports good growth of these cells when supplemented with insulin, hydrocortisone, EGF and less than 1% serum. The goal of this phase of our research is to develop defined medium assay systems and to use them to study the mechanisms of tumor angiogenesis and its inhibition.